Julia Blackburn's The Book Of Colour is written from the point of view of her father and grandfather, who lived on Mauritius, while Marianne Wiggins's Eveless Eden tells of the love affair of Noah John, a journalist on a New York newspaper.
The book world will wait with glee to see if Ms Wiggins wins the pounds 30,000 award, because - in a further irony - the original suggestion for the prize came from her estranged ex-husband, Salman Rushdie.
They have had little contact since she left her husband after spending five months in hiding with him, and accused him of being self-obsessed and a coward. They divorced in 1993.
The Orange Prize is open to women of all nationalities who write in English, and two of the other three shortlisted are American: Anne Tyler for Ladder Of Years, and Amy Tan for The Hundred Secret Senses.
The final places on the shortlist have been taken by Helen Dunmore for A Spell Of Winter and Pagan Kennedy for her first novel Spinsters.
The Orange Prize has attracted controversy since it was announced in January, with accusations of sexism and ghettoism fuelled by its value; it is worth pounds 10,000 more than the Booker and pounds 9,000 more than the Whitbread award.
Kate Mosse, chairwoman of the judges, said at the launch that the prize had been partly inspired by the Booker's 1991 shortlist when all six authors - including Martin Amis, Ben Okri and Roddy Doyle - were men.
"Just imagine what people would say if Booker released a shortlist with only women. Everyone would see it as an enormous political statement," Ms Mosse said then.
"We're not complaining, stamping our feet and saying, `This isn't fair'. But whether from taste, tradition or expectation most women don't find their way on to shortlists and even fewer actually win."
AS Byatt, herself a Booker winner, has said that the reason few women have won is because they have not in general been as good as men.
The longlist for the Orange Prize, leaked to the Bookseller this week, yields an interesting selection of writers who did not make the shortlist. They include Pat Barker, who won the Booker last year for The Ghost Road, a book about a typically male subject, war, and with a cast of largely male characters.
The first Orange Prize will be awarded on 15 May.
Polly Toynbee, page 15